It is known in the art that when a thin plate (hereinafter referred as a magnetic thin plate) formed by a rare earth orthoferrite, a magnetic garnet, an amorphous magnetic substance or the like in such a manner that its crystal C-axis is perpendicular to the plane of the thin plate is impressed with an appropriate DC magnetic field (hereinafter referred as a bias magnetic field) in a direction perpendicular to the plane of the thin plate, cylindrical magnetic bubbles (hereinafter referred as magnetic bubbles) magnetized in a direction opposite to the bias magnetic field are produced in the magnetic thin plate. Since this magnetic bubble can be shifted in a plane in the magnetic thin plate under maintaining its cylindrical configuration by providing a gradient of the bias magnetic field at both ends of domain walls defining the magnetic bubble, it is possible to achieve memory or logical operations of information by respectively utilizing the presence and absence of the magnetic bubble as binary information 1 and 0. Various information processing circuits of this type are now produced.
Many kinds of systems have been known for transmitting a magnetic bubble in the magnetic thin plate. One of the known systems is of such a type, in which a soft-magnetic thin film of a specific form is disposed in close contact with the magnetic thin plate so that the magnetic bubble is shifted-and-transmitted in one direction by repeatedly reducing and restoring the magnitude of the bias magnetic field under a condition where the magnetic bubble is coupled with the soft magnetic thin film in a manner to minimize its magnetostatic energy.
However, the above system necessitates the use of a coil for reducing and restoring the magnitude of the bias magnetic field, so that the apparatus therefore becomes inevitably large in size as a whole. Attempting to reduce the overall size of the apparatus by applying the bias magnetic field to the magnetic thin plate under a fixed bias method using a permanent magnet or a self bias method in place of the coil, the reduction and restoration of the bias magnetic field become difficult to achieve and this system cannot be used. Further, in this system, when the bias magnetic field is reduced or restored in its magnitude, all magnetic bubbles present in the magnetic thin plate simultaneously move, so that this system is not suitable for the making of circiuts which have a higher degree of function in addition to a memory function.